This proposal is designed to develop a data base of cell kinetic parameters of human colorectal tumors. Primary, as well as metastatic, tumors will be studied and results will be correlated with clinical course, biologic markers, and pathology. The studies will be performed totally in vitro at speeds compatible with potential clinical usefulness. In addition, these in vitro results will be compared to in vivo studies in selected patients. A G.I. Oncology Fellow will be the coordinating force in sample collection. When results become available pilot chemotherapeutic studies, systemic as well as by infusion, will be initiated.